Introduction
Demographics
Fractures involving the tibial articular surface account for a little over 1% of all long bone fractures, 56.9% of all proximal tibia fractures/dislocations, and 8% of all fractures in the elderly. These fractures have an annual incidence of 10.3 per 100,000. The combined incidence of a patient having a tibial plateau fracture with associated polytrauma on admission has been estimated at 16% to 40%. The age distribution is bimodal for both males and females, which is similar to what is seen in other periarticular injuries. The majority of fractures occur in males (70%), with men aged 40 to 44 years being the most affected patient population overall. , Comminuted fractures are more common in males. There is a shift of incidence between males and females that occurs after the age of 60, with females (61%) predominating. , With an increase in life expectancy and a large aging population in many developed countries, it is expected that the incidence of low-energy tibial plateau fractures will continue to increase. Medical comorbidities and certain medications can affect bone quality, increase the risk of postoperative infection, and inhibit wound healing.
Mechanism of Injury
The mechanism of tibial plateau fractures varies by the age of the patient. The majority of tibial plateau fractures in the elderly are due to low-energy falls. Osteopenia and osteoporosis play a large role in the fracture mechanisms and patterns observed. The forces acting on bone determine the resulting fracture patterns in conjunction with bone quality. Low bone density decreases the force necessary for injury. In the elderly, lateral fracture patterns are seen more commonly than medial ones. A higher incidence of compression fracture patterns tends to be seen in such cases with lower-energy injury mechanisms. In younger individuals, high-energy mechanisms predominate. The injury mechanism can involve motor vehicles, sports, and falls from height. The most common mechanism of injury overall is pedestrians being struck by motorized vehicles (30%), followed by low-energy falls (22%).
The magnitude and direction of the injury force will often influence the fracture pattern. Angular, axial, and compression forces can all lead to failure of the condyles. Axial load is usually a predominant component of the injury mechanism and produces higher energy at failure than angular forces. In general, greater axial load results in more severe fractures with increased comminution, fragment displacement, and associated soft-tissue injury. In a cadaver study that looked at mechanisms of injury, it was found that pure valgus forces resulted in the typical lateral split fractures, axial forces resulted in joint compression fractures, and a combination of axial and valgus forces resulted in split depression fractures. In isolated lateral plateau fractures, the medial collateral ligament can act as a pivot point causing the lateral femoral condyle to impact the lateral tibial plateau. The proximal tibia is more vulnerable to valgus force because of the 5 to 7 degrees of knee valgus in normal anatomic alignment. In addition, lateral side impacts tend to occur as a common injury mechanism in these fractures.
Clinical Evaluation
Initial Emergency Department Evaluation
Evaluation and management of tibial plateau fractures in the emergency department will set the stage for successful patient outcomes. One should suspect a tibial plateau fracture in a patient who presents with pain and tenderness around the knee following an injury. The pain may be localized to the proximal tibia at the fracture site. The patient may present with a visible knee hemarthrosis secondary to an intraarticular fracture. The patient may also report deep pain secondary to a ligamentous or meniscal injury. Evaluation of a suspected tibial plateau fracture begins with a history and physical examination, as described later. The reported mechanism of injury is important to determine, as it helps predict the severity of the injury, the fracture pattern, and the associated injuries. For example, a fall from standing is a low-energy mechanism, and the risk of associated soft tissue, neurovascular injury, or compartment syndrome (CS) is low. However, if the mechanism is of high energy (as seen with motor vehicle accidents, a pedestrian struck, or a fall from height), then a higher degree of vigilance is necessary to detect associated injuries that may require urgent or emergent management. A thorough physical examination results in the diagnosis of associated injuries and helps establish future surgical timing and treatment.
Examination of the soft-tissue envelope will reveal the presence or absence of significant swelling, abrasions, blisters, and open injury. Open fractures require immediate antibiotics as the delay in the initial dose of antibiotic administration markedly increases the risk of infection. Antibiotic coverage is guided by the severity of injury and contamination and typically includes coverage for gram-positive bacteria. If the open fracture injury appears to be of higher severity, prophylaxis against gram-negative organisms is recommended, and in the case of soil contamination, penicillin may be added as well. , As previously discussed, a thorough neurovascular examination should be performed. Any neurological deficits should be documented, whether complete or partial. There is a higher incidence of peroneal stretch injuries with medial plateau and higher-energy mechanisms. If there are abnormalities of the distal leg pulses, further evaluation should ensue, including ankle-brachial index (ABI) measurement and possibly additional evaluation with a computed tomography arteriogram (CTA) or vascular consultation. Furthermore, the importance of assessment of the leg compartments cannot be overemphasized. If CS is evident, based either on classic signs and symptoms or on measured compartment pressures, plans should be set in place for urgent fasciotomies. Patients who present with injury following high-energy mechanisms should be strongly considered for close observation for the development of CS.
Radiographs ultimately guide treatment decisions and determine the risks of associated injuries. A CT scan is often necessary to optimally characterize a tibial plateau fracture; however, it should not always be ordered during the emergency department evaluation. When temporary external fixation is planned and fracture comminution and shortening are present, CT scans will provide a better picture of the fracture fragments after the application of an external fixator.
History
It is important to obtain a thorough history in all tibial plateau fractures. One should attempt to determine the mechanism of injury, its severity, and whether there is a need for emergent management. Low-energy falls or twisting injuries are less likely to cause neurovascular injury or CS, whereas falls from height, motor vehicle accidents, and pedestrians being struck by a vehicle may necessitate more urgent management. The fracture pattern is important in determining the treatment approach and risk of complications. The location and severity of pain, the timing of the injury, the associated injuries, and any treatments administered are helpful pieces of information. One should also assess tobacco use, prior knee problems, ambulatory status prior to the injury, and medical comorbidities such as pulmonary disease, diabetes, vascular disease, cancers, renal disease, nutritional deficiencies, previous poor dual-energy X-ray absorptiometry (DEXA) scan results, as well as the use of immunosuppressive medicines. Medical comorbidities and certain medications can affect bone quality, increase the risk for postoperative infection, and inhibit wound healing. The patient’s activity level, social support, mental condition, and employment status should be known in order to make an appropriate treatment plan and manage postoperative expectations.
Physical Examination
As a part of the initial assessment of tibial plateau fractures, one should attempt to rule out soft-tissue compromise, open fractures, CS, and neurovascular injury. The injured limb should be circumferentially assessed, paying special attention to the overlying skin and the neurovascular baseline status. Circumferential skin and soft-tissue inspection and palpation should be done to assess for open injury and severity of soft-tissue injury. The severity of soft-tissue injury may be further described by the size, character, and location of swelling, contusions, and fracture blisters. Soft-tissue assessment is key to determining surgical approaches and timing.
A noncompressible, firm extremity, paresthesias, and pain with passive stretching suggest CS. Because it can develop even days after injury, CS should be monitored for throughout the patient’s stay. Consideration should be given to measuring compartment pressures in those with high-energy fracture patterns or in unresponsive patients, and this may need to be repeated based on clinical assessment. Whether diagnosed by elevated compartment pressures or by physical examination alone, CS is treated by urgent fasciotomy. More details on CS are given later.
For high-energy injuries, especially fracture-dislocations and metaphyseal-diaphyseal dissociation patterns, it is imperative to obtain a thorough neurovascular assessment. Vascular injury is rare overall, but delays in diagnosis and surgical intervention by more than 8 hours can result in lower extremity amputation rates as high as 86%. Neurovascular assessment should include testing for sensation patterns in the distribution of the tibial, superficial peroneal, saphenous, and sural nerves, and motor function of the tibial and peroneal nerves. Likewise, it should include extremity color assessment, capillary refill, and palpation of the distal pulses, including the posterior tibial and dorsalis pedis arteries. Findings should be compared with the contralateral side. Any differences in pulses or sensation can be further investigated with an ABI measurement. For some high-energy fractures, one might obtain an ABI regardless. An ABI >0.8 has a remarkably high negative predictive value, approaching 100%. With ABI <0.9, further vascular assessment with a CTA and/or a vascular surgery consultation should be obtained.
If instability is suspected but not clear on radiographic assessment, varus and valgus stress testing may be required. Valgus instability is a potential indication for surgical management, especially in lateral tibial plateau fractures. Instability may not resolve without surgical fracture reduction and fixation. ,
Imaging and Evaluation
Imaging is a critical part of the initial evaluation. Imaging modalities range from plain radiographs to CT with three-dimensional reconstruction and magnetic resonance imaging (MRI). Imaging is necessary to evaluate the injury and determine what type of treatment may be necessary.
Plain Radiographs
Plain radiographs are usually the first imaging study to evaluate suspected tibial plateau fractures ( Fig. 2.1 ). For some simple fractures, this may be the only imaging modality necessary. Typically, one orders anteroposterior (AP) and lateral view plain radiographs of the knee. An additional view, the caudal view (also known as the “tibial plateau view”), is shot 10 to 15 degrees caudally from a typical 90-degree AP view. This is done to account for the 15-degree posteroinferior slope of the plateau surface. The caudal view plain radiograph provides a view in line with the plane of the plateau. In this view, the proximal articular surface can be viewed as a single radiodense line that allows better assessment than lateral and AP views of articular depression. One should also obtain radiographs of the entire tibia. Oblique views were once used to assess the fracture lines and degree of displacement; however, CT scans have largely replaced them. Notably, it has been shown that plain radiographs alone can miss insufficiency fractures in osteopenic patients.
Results of plain radiograph imaging can guide treatment decisions and determine the risks of associated injuries. Radiographic indications for surgery include lateral fractures with more than 5 degrees of valgus tilt, medial plateau fractures, bicondylar fractures, articular depression greater than 3 mm, and condylar widening greater than 5 mm. The AP radiograph may show articular surface depression and dense-appearing subchondral bone, which are indicative of a compression injury. The alignment of the knee joint and the fracture pattern can also be assessed from the AP view. Fractures that split and depress the lateral plateau have a higher incidence of associated lateral meniscus tears. Medial tibial plateau fractures usually require high-energy mechanisms; thus, the suspicion of a fracture-dislocation in these cases should be high. Medial tibial plateau fractures demand a careful neurovascular examination, and ABI measurements may be needed. Additionally, fractures of the medial plateau are associated with a high incidence of medial meniscal tears and ACL rupture. ACL rupture has also been shown to have a significant association with fracture patterns including metaphyseal-diaphyseal separation. , Lateral radiographs are used to evaluate the medial plateau and may reveal coronal split fractures. Coronal split fractures are more common within the medial plateau and are often missed on the AP view. A fracture with a large posteromedial fragment may necessitate a posteromedial approach for appropriate fixation.
Somewhat counterintuitively, patients with fractures with up to 10 mm of articular depression and joint stability have acceptable functional outcomes in long-term studies; however, joint instability in the context of certain other factors such as articular step-offs and central joint depression results in poor outcomes. Additionally, more than 5 degrees of limb malalignment may triple the rate of posttraumatic degenerative arthritis.
When there is substantial displacement, traction radiographs can be used to assess the fracture anatomy in both plain radiographs and CT scans. This can be obtained by manual traction or spanning external fixators. In severely comminuted fractures, contralateral radiographs may provide a template for reduction including condylar width, coronal alignment, and the posterior slope of the plateau in the sagittal plane.
Computed Tomography
CT scans have become a routine part of the assessment of tibial plateau fractures ( Fig. 2.2 ). Axial CT cuts are especially helpful in visualizing posteromedial fracture lines not evident on plain radiographs. Axial CT and reconstructions provide important insight into fracture anatomy and serve as an aid in preoperative planning. It has been demonstrated in numerous studies that the use of CT scans in addition to plan films allows surgeons to more reliably classify fractures, which aids in providing the most appropriate treatment. CT reveals articular displacement and comminution more readily than plain radiographs. CT also allows for better assessment of the location and orientation of fracture lines, the degree of depression, and the size of articular segments, which provide important information in preoperative planning.
As in the interpretation of plain radiographs, one should evaluate CT imaging studies systematically. The appearance of lipohemarthrosis on CT indicates an intraarticular fracture and is most commonly seen with occult tibial plateau fractures. Complex fracture patterns are more clearly delineated on CT. One should rule out the presence of posterolateral and posteromedial fracture fragments, which often require adjunct fixation. These fragments sometimes occur in bicondylar tibial plateau fractures. The posterolateral fragment may appear as an inverted conical shape that is vertically oriented and occupies one-third of the lateral plateau surface. The posteromedial fragment is often defined by any posteriorly based articular fracture that exits the medial cortex and is often best visualized on axial CT images. Failure to address these fragments can result in fracture malreduction and postoperative complications.
Magnetic Resonance Imaging
MRI is increasingly used to evaluate tibial plateau fractures. Some argue that only MRI can adequately show soft-tissue injuries, especially those associated with high-energy fractures, which often cause ligamentous and meniscal pathology. MRI is more sensitive than CT in detecting ligamentous and meniscal injuries that are both common occurrences in tibial plateau fractures. Like CT, MRI ( Fig. 2.3 ) will detect lipohemarthrosis. MRI is the gold standard when it comes to detecting occult fractures not seen on plain radiographs.
Compartment Syndrome
CS is a limb- and sometimes life-threatening condition that can lead to devastating outcomes if not appropriately diagnosed and treated. CS is often associated with trauma or other conditions that cause bleeding, edema, or vascular compromise and causes increased pressure within a myofascial compartment of the body. Because the fascia and connective tissue are inelastic, increased intracompartmental pressure eventually compresses the thin-walled veins, leading to venous hypertension and eventual tissue ischemia. Muscle necrosis can occur as quickly as 2 hours after onset of CS. Irreversible nerve damage occurs 6 to 8 hours after onset. Given the high-energy nature of the injuries, tibial plateau fractures are often associated with CS. The reported incidence varies, though one study reports a 53% incidence of CS in Schatzker type IV tibial plateau fractures. The overall incidence of CS following tibial plateau fractures varies in the literature from 1% to 11%. Several studies on tibial plateau fractures suggest that acute CS contributes to postoperative complications such as nonunion and infections. Acute CS needs to be appropriately recognized, diagnosed, and managed to prevent both acute and long-term complications for patients.
Early recognition and diagnosis of CS is critical to the overall outcome. The diagnosis is often clinical, although this can be challenging at times. The common clinical signs of CS include worsening pain out of proportion to the situation, pain with passive stretch (passive plantar flexion of the big toe), paresthesias, pulselessness, and poikilothermia. However, these clinical signs have been shown to have low sensitivity for diagnosing CS. Additionally, clinical diagnosis can be difficult in polytrauma patients with distracting injuries or those too obtunded to report symptoms or show clinical signs (e.g., those who are intubated or sedated). Intracompartmental pressure measurement can be another useful diagnostic tool to diagnose CS. CS is diagnosed when the difference between diastolic blood pressure and compartment pressure is less than 30 mmHg (delta P). However, it is important to note that patients under anesthesia can have falsely decreased diastolic pressures, which may lead to overdiagnosis of CS and unnecessary fasciotomies, as described by Kakar et al. It has also been shown that a single compartment pressure measurement with delta P < 30 mmHg may not be clinically significant. One study showed that measuring delta P < 30 mmHg for 2 or more consecutive hours has a sensitivity of 94% for CS. Compartment pressures can also vary based on the proximity to the fracture site and the depth of measurement. Studies have shown that the highest pressure measurements will be obtained within 5 cm of the fracture and centrally in the muscle. Surgeons must have a high index of suspicion for CS in tibial plateau fractures. When it is diagnosed, emergent fasciotomies are necessary to prevent irreversible limb and life-threatening complications ( Fig. 2. 4 ).
Technique
In the case of CS associated with tibial plateau fractures, the authors recommend four compartment fasciotomies performed through medial and lateral incisions (two-incision technique). An anterolateral longitudinal incision is made from the proximal tibial metaphyseal-diaphyseal junction to the distal tibial metaphyseal-diaphyseal junction. The incision is centered between the lateral border of the tibia and the anterior border of the fibula. Subcutaneous tissue is incised down to fascia. In the midportion of the wound, a transverse incision is then made in the fascia and the intermuscular septum is identified and palpated. The anterior compartment fascia is then incised along the entire length of the tibia with an incision of the fascia anterior to the intermuscular septum. A fascial incision posterior to the intermuscular septum along the length of the tibia releases the lateral compartment while taking care to avoid injuring the superficial peroneal nerve. Fascial release can be performed with a scalpel, scissors, or a combination thereof ( Fig. 2.5 ).
